EcoRenovator  

Go Back   EcoRenovator > Improvements > Solar Power
Advanced Search
 


Blog 60+ Home Energy Saving Tips Recent Posts Search Today's Posts Mark Forums Read


Reply
 
Thread Tools Display Modes
Old 06-03-16, 08:38 PM   #11
MEMPHIS91
Journeyman EcoRenovator
 
MEMPHIS91's Avatar
 
Join Date: Apr 2015
Location: Oxford, MS USA
Posts: 496
Thanks: 69
Thanked 87 Times in 61 Posts
Default

I'm trying to do away with batteries all together.
I have panels, I have window unit, I do not, will not, never tie into the grid. I refuse to sleep with the enemy no matter how "good" it might be. I'm stubborn and it will probably be the death of me, but so be it.

Basically I only need the grid to "jump start" the window unit and then switch over to solar if the sun is out. No sun = less heat, less heat = less need of AC unit. I am just trying to use the extra power I have.

Questions, can you run one appliance from 2 power sources at the same time? Lets say 2 generators? A gen and the grid? Solar and gen? Or like the way I want it solar and the grid. Lets say the sun is shinning on half the panels, so 400 watts or so. And the unit need 480, is there a device, or can a device be made that would allow the 80 watts to be pulled from the grid and 400 from the panels? Crazy I know, but that really is what I'm asking, if this can't be done that is fine, I will just bury the idea and move on.

__________________
שְׁמַע יִשְׂרָאֵל ה' אֱלֹהֵינוּ ה' אֶחָד
MEMPHIS91 is offline   Reply With Quote
Old 06-03-16, 10:05 PM   #12
NiHaoMike
Supreme EcoRenovator
 
NiHaoMike's Avatar
 
Join Date: Oct 2008
Location: Austin, TX
Posts: 1,154
Thanks: 14
Thanked 257 Times in 241 Posts
Default

V/Hz soft start will help considerably in reducing the peak power needed. In fact, you'll likely be limited by oil return issues. Expect maybe a 3:1 dynamic range using an off the shelf compressor. You might be able to improve that by adding some supercaps and using them to allow variation for an oil return cycle.

But it seems like a "cheap" grid tie inverter would probably be your best bet. As long as you're running the loads when the solar is producing, the "50% loss" won't come into play. It doesn't export to the grid only to reimport it - it goes to the load and import/export only comes into play to balance things out.
__________________
To my surprise, shortly after Naomi Wu gave me a bit of fame for making good use of solar power, Allie Moore got really jealous of her...
NiHaoMike is offline   Reply With Quote
Old 06-04-16, 11:31 AM   #13
MEMPHIS91
Journeyman EcoRenovator
 
MEMPHIS91's Avatar
 
Join Date: Apr 2015
Location: Oxford, MS USA
Posts: 496
Thanks: 69
Thanked 87 Times in 61 Posts
Default

NiHaoMike, So your saying that if I bought a grid tied inverter and ran, lets say all my panels for sake of this idea, directly into the grid tied inverter and the inverter tied into ANY outlet in the house. As long as the house electric load was greater than the output of the panels then I wouldn't be sending any power to the grid, and would be using 100% of what the panels are making. So if my house load was 6000 watts and my panels where making 1000 watts, then I would be only using 5000 watts from the grid?
If this is what you are saying, that would be awesome, because my power company just started doing higher rates in the heat of the day. Meaning I would be saving the most money when the sun is shinning. =D

Thank you sir, this is awesome.
__________________
שְׁמַע יִשְׂרָאֵל ה' אֱלֹהֵינוּ ה' אֶחָד
MEMPHIS91 is offline   Reply With Quote
Old 06-04-16, 02:36 PM   #14
MEMPHIS91
Journeyman EcoRenovator
 
MEMPHIS91's Avatar
 
Join Date: Apr 2015
Location: Oxford, MS USA
Posts: 496
Thanks: 69
Thanked 87 Times in 61 Posts
Default

My power company just distributes TVA power, I talked to a buddy work works for my power company and he said in 2018 they will no longer pay anything per kWh. Meaning a battery type setup or what I'm talking about is the only way. And I just checked again, the rates dropped in 2016 to 5cents a kWh Tennessee Valley Authority cutting back solar incentives
__________________
שְׁמַע יִשְׂרָאֵל ה' אֱלֹהֵינוּ ה' אֶחָד
MEMPHIS91 is offline   Reply With Quote
Old 06-04-16, 03:12 PM   #15
stevehull
Steve Hull
 
Join Date: Dec 2012
Location: hilly, tree covered Arcadia, OK USA
Posts: 826
Thanks: 241
Thanked 165 Times in 123 Posts
Default

Memphis,

You are correct in terms of understanding power balance. If you are using 6000 watts (5 kW) and the PV panels are putting out 1 kW, then you are only billed for the difference (5 kW).

Here is where you need to do some homework. Explore your utility bills and plot your monthly kWhrs used in each month. Your electricity use will likely be lower in the winter (in your location in the south) as you are not using AC at that time.

Then build a PV system that is just under the maximum you need for any month in the summer. You need to use PVwatts to do this as it will calculate your historical sunshine hours for your specific location. Not every day is 100% sunny . . .

In this way, you don't use the grid for anything, but you do use the 240 and 120 V wiring in your home.

I suspect that a 6 kW array (24 250 watt panels) would put a huge dent in your bill. The great thing about being in the south is the summer, when AC use is high, is also when the PV panels put out the most power.

Does this make sense?

Steve
__________________
consulting on geothermal heating/cooling & rational energy use since 1990
stevehull is offline   Reply With Quote
The Following User Says Thank You to stevehull For This Useful Post:
jeff5may (06-04-16)
Old 06-04-16, 03:20 PM   #16
natethebrown
Apprentice EcoRenovator
 
Join Date: Aug 2012
Location: North Alabama
Posts: 167
Thanks: 0
Thanked 40 Times in 20 Posts
Default

Quote:
Originally Posted by MEMPHIS91 View Post
My power company just distributes TVA power, I talked to a buddy work works for my power company and he said in 2018 they will no longer pay anything per kWh. Meaning a battery type setup or what I'm talking about is the only way. And I just checked again, the rates dropped in 2016 to 5cents a kWh Tennessee Valley Authority cutting back solar incentives
Bummer, this impacts me too!
natethebrown is offline   Reply With Quote
Old 06-04-16, 04:34 PM   #17
MEMPHIS91
Journeyman EcoRenovator
 
MEMPHIS91's Avatar
 
Join Date: Apr 2015
Location: Oxford, MS USA
Posts: 496
Thanks: 69
Thanked 87 Times in 61 Posts
Default

Steve, yes that is the plan, I would love to do exactly what you are saying, and yes wait til battery prices are much better before going off the grid.
But I have 800 watts of panels hooked to nothing. I have a window unit that I can use in my upstairs bedroom to help with the higher heat up there.
I don't have the money (right now) to drop into more panels.
So that is why I'm trying to make do with what I have.
But I really do appreciate your replies because I will be going that route in the future.

Natethebrown. yes it is bummer. If my power company gave me as much as they charge me and committed to a long term plan, I would LOVE to grid tie.
__________________
שְׁמַע יִשְׂרָאֵל ה' אֱלֹהֵינוּ ה' אֶחָד
MEMPHIS91 is offline   Reply With Quote
Old 06-04-16, 10:40 PM   #18
jeff5may
Supreme EcoRenovator
 
Join Date: Jan 2010
Location: elizabethtown, ky, USA
Posts: 2,428
Thanks: 431
Thanked 619 Times in 517 Posts
Send a message via Yahoo to jeff5may
Default

The 250 wattt micro-inverters are about the smallest you can get. The generic ones start off about 70 dollars, the emphase ones are around 250. Like most electronic equipment, you generally get what you pay for...
jeff5may is offline   Reply With Quote
Old 06-05-16, 05:44 AM   #19
MEMPHIS91
Journeyman EcoRenovator
 
MEMPHIS91's Avatar
 
Join Date: Apr 2015
Location: Oxford, MS USA
Posts: 496
Thanks: 69
Thanked 87 Times in 61 Posts
Default

Jeff, yeah you are very right. I found a 600 watt for $100 that I'm going to try,its worth $100 to see if this idea works. I normal have 350-600 watts of things running when the sun is shinning anyway. That should make sure I never send power back to the grid. I'm going to put a timer on the heat pump hot water heater to only run during those times as well. This by no means is a perfect setup. But that cheapest route to use the equipment that I have just laying around. I have a meter on my house that I can use to see how much it is really helping.
__________________
שְׁמַע יִשְׂרָאֵל ה' אֱלֹהֵינוּ ה' אֶחָד
MEMPHIS91 is offline   Reply With Quote
Old 06-05-16, 06:38 AM   #20
stevehull
Steve Hull
 
Join Date: Dec 2012
Location: hilly, tree covered Arcadia, OK USA
Posts: 826
Thanks: 241
Thanked 165 Times in 123 Posts
Default

Jeff,

Check your prices on Enphase M250's here (Renvu.com). About $125 each, not $250. And the newer S280 is not much more.

I have bought from Renvu after looking at many sales outfits. I REALLY like the Enphase units with the non prorated 25 year guarantee though Siemans. Had to replace one that failed early on an install and the Siemans warantee rep was frankly dubious of the failure until I walked him thorough my diagnostics. Had another one in less than a week.

Memphis - these just plug into your 240 V line and electrically are "silent" to the grid electric utility. Your existing panels can be easily hooked up for just a few hundred $.

Steve



ENPHASE ENERGY M250 IG Grid-Tie Microinverter | RENVU

__________________
consulting on geothermal heating/cooling & rational energy use since 1990
stevehull is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 10:28 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Ad Management by RedTyger
Inactive Reminders By Icora Web Design